im going to be getting akegging system for xmas. i have a batch that i need to bottle. can i pick up a corney keg an prime my beer and put it in a keg till xmas?
or should i just pick up some more bottles?

A keg is just like a big bottle. You can age beer in it as well. The only issue I see is that you cannot purge the oxygen out of the keg. Once filled you need to put the keg on gas and pull the relief a few times to make sure there's no oxygen in the kegs headspace.

Ordered the 2 keg party kit. It's technically a christmas gift.
So when I get it I should soak the keg in oxyclean, then sanitize, put my cream ale in close it up. Then just purge the o2 and seet the lid? Then I can just leave it disconnected from the co2 until Xmas when I get my freezer?

I'm on my second attempt with a corney. The first time I just force carbed and I got a terrific Ale in about 1 week. This time I added 3/4 cup of priming sugar to the batch (I made 10 bottles too) before kegging it. I have it under pressure at 12PSI. Am I going to over carb this? Am I screwing this up.

I've made a good 10+ batches of beer and prime the keg, let it sit, and then when I need it, put it on gas. I've never had an issue with overcarbing.
The only thing I will say, I have read somewhere when I started researching getting into this hobby, I went straight to kegging, that you only need 1/3 cup of sugar to prime a keg with.

this is true, it is much less than bottling the same volume. I overcarbed a couple before I learned that.

The beauty of it is that you can just purge out the gas over a couple of day and fix it no problems. No such thing as keg bombs. (well, I guess you never say never, but if someone has blown up a corny, I want to hear about that!

__________________Reformation Brewery: We went professionalObsessing over: starting a local brewery (hence I am not here much these days!), Pickles, my wife, 3 year old and 6 year old
Reading: fall of giants by ken follett
Building: gardens, recipes, and trailer mounted smoker/ wood pizza oven